When you first turn on your amplifier, a massive inrush current gushes in. Your house lights flicker as you hear loud "thump" from your amplifier. This terrible inrush current stresses all your power supply components to their limits. Your cold tube filament suffers abusive thermal shock.
Eventually, this massive inrush current will damage your amplifier.
Ameritrons Step-Start Inrush Current Protector stops damaging inrush current. By starting your linear amplifier through a high power current limiting resistor and then shorting the resistor with a relay, you get a start up sequence thats easy on your tube and power supply components.
Ameritron ICP-120, $79.00, for 120 volt wired amplifiers. Limits current to 12 amperes during heavy draw inrush period. 20 amperes continuous operating current.